Bifocal lens.



A. J, (moss. BIFOGAL LENS. APPLICATION FILED DBO. 19, 1913.

Patented June; 30,1914.

UNITED STA; 'jj;

ANDREW JAY CROSS, OF

NEW YORK, N. Y.

BIFOCAL LENS.

Specification of Letters Patent.

Application filed December 19, 1913.- Serial NOI Patented June 30, 1914.

ing drawings forming a part of this specication, in which similar reference characters indicate corresponding parts in all the views.

Figure l is an inside elevation 0 s owing my improvemen Fig. 2 1331/1011- .i 3 is a cross Fig. 1, and Fig. 4 line 4+4 of Fig. 1

invention relates to improvements in bifocal lenses, and the general objectof my invention islto produce a bit'ocal lens for close vision member 10 of the glass or lens, and the negative mem- Where the lens is made in two pieces, the I is made the full size the lens has a much greater area than usual 1 the distance lens 18 cut awa in bi cal lenses, this ing accomplished in or has a portion removed at its lower edge away which does not appreciably reduce the as shown at 12, this being curved up in the istance area of the lens.

Heretotore the general struction of bifoeallenscs has been to cement or fasten to the distance glass a positive segment which provides the close vision or reading member of the lens. This positive or close vision segment has been constructed chanical difliculties of grinding are so g as to render it practically impossible to center to provide the necessary close vision area, and the exposed ractice in the conpart of the member 10 cause many people object tothe appearance of bifocal lenses.

It will be readily seen that to grind a segment corresponding to the sh ape of the ex- 1 ig. l, segment and'adapted to be secured to a' distance lens as usual, would be practically impossible, owing to the mechanical difiiculties of actually grinding and aflixing a member of such shape, but it is a very simple matter to cut the lower e e of the I the lens disclosed, and if the lens is made in a single iece, a tool can be devised 'for shaping t e lens as described.

It will be noticed by reference to Fig. l,

wider area to the reading or close vision member, and it is also plish this result, though manner, by what is called solid grinding,

that is by grinding a mg the middle portion of the close vision member substantially as usual, but by Widening the exposed portion of said memer at its lower edge, very satisfactory results are obtained, and the user of the lens has a much wider range of vision through the close vision member than has heretofore been possible. This makes the glasses in which such close vision area is much greater, and especially much wider, which is very desirable.

In the construction which I have shown and-described, it

as in a case where the segments are added,

principal axis, and grows thicker toward the ends to. Reference is to be had to the accompany member 10 inmember 11 oi"- will be noted that the ex 75 away at the upper edge of the member. This, as stated, leaves the close vision exposurein the form of a depression, and makes it possible to have the principal axes of the two members 10 and 11 2. As an improved article of manufacture,

a bifocal lens having its lower or close vision plete Licence.

member highest in the center, and with its upper edge curving downward, outward, and finally upward, thereby leaving the whole lower edge portion of the lens clear and "adapted for close vision. A lei-focal lens comprising'a complete member r'orming the close vision portion of the lens, and an incomplete member superimposed on the complete member, the incommember having its lower edge portion formed in the shape of a compound curve, highest in the center, and curving downward, outward and upward at the sides, thereby leaving a clear field for the close vision member along the entire lower portion of the complete lens.

ANDREW JAY CROSS. Witnesses:

WARREN B. Hurcnmson, ARTHUR Gr. DARNELL. 

